parthenogenesis

gametogenesis

asexual reproduction

simple to produce many copies
can reproduce asexually even if isolated
can reproduce rapidly
more prevalent in species that live in stable environments with little selection pressure for genetic diversity

leukocytes

active immunity

passive immunity

Direct transfer of antibodies from one individual to another
Naturally via placenta or breast milk
Artificially when human patient given IgG molecules (for example after exposure to hepatitis)
S hort-lived because memory cells are not produced